Optimal cutting condition and maximal tool force in circular rock cutting. Study on disc cutting of rock (2nd Report).

A study of disc cutting was carried out for seven selected rocks occurring in Japan, Korea and China using a circular rock cutting testing rig. The aim of the study programme was to establish: the optimal conditions for disc cutting, to find the relationship between the peak tool force and the mean tool force and to estimate the effect of the radius of the cutting track on the lateral component of the tool force. The main conclusions of the study are: the optimal ratio of tool space to disc penetration that allows the specific energy of rock excavation to be minimised depends on the fracture toughness and the uniaxial compressive strength of rock; the specific energy at the optimal cutting condition correlates linearly with the uniaxial compressive strength of the rock; all the components of tool force vary around their mean values, resulting in stochastic process - the lateral force fluctuates more than the rolling force, although their mean values are comparable to each other; the peak tool force is in proportion to the mean tool force - the magnification of peak to mean is 1.33, 1.60 and 1.63 for the thrust, the rolling force and the lateral force respectively, regardless of different types of rocks; and the magnitude of lateral force does not depend on the radius of the cutting track when rocks between neighbouring tracks are cut off completely - lateral force is always directed towards the adjacent cutting track.
A study of disc cutting was carried out for seven selected rocks occurring in Japan, Korea and China using a circular rock cutting testing rig. The aim of the study programme was to establish: the optimal conditions for disc cutting, to find the relationship between the peak tool force and the mean tool force and to estimate the effect of the radius of the cutting track on the lateral component of the tool force. The main conclusions of the study are: the optimal ratio of tool space to disc penetration that allows the specific energy of rock excavation to be minimised depends on the fracture toughness and the uniaxial compressive strength of rock; the specific energy at the optimal cutting condition correlates linearly with the uniaxial compressive strength of the rock; all the components of tool force vary around their mean values, resulting in stochastic process - the lateral force fluctuates more than the rolling force, although their mean values are comparable to each other; the peak tool force is in proportion to the mean tool force - the magnification of peak to mean is 1.33, 1.60 and 1.63 for the thrust, the rolling force and the lateral force respectively, regardless of different types of rocks; and the magnitude of lateral force does not depend on the radius of the cutting track when rocks between neighbouring tracks are cut off completely - lateral force is always directed towards the adjacent cutting track.